Double Opt-in

Please Confirm That You Want To Read About Double Opt-in

By Kath Pay

Double Opt-in is not a requirement of GDPR. Providing evidence of consent is, and DOI just one of the many ways you can provide evidence.

MailChimp have changed to being to Single Opt-in (SOI) after being Double Opt-in (DOI) for many years. An interesting move and one I see the logic in.

Since the news was released, some people have raised a concern, as they believed DOI to be a legal requirement of the upcoming European GDPR legislation, that Mailchimp are not assisting marketers to be GDPR compliant.

Firstly, Double Opt-in is not a requirement of GDPR. Providing evidence of proof is, and DOI just one of the many ways you can provide proof. The GDPR has been designed to be future-proofed and as such does not require any particular technology process to be compliant.

Secondly, Mailchimp have not done away with the ability to use DOI, they’re just now making the default SOI, whereas before, unless you used a workaround, DOI was your only option.

So, let’s look at some facts.

  • MailChimp was one of only a couple of email service providers who made DOI mandatory. The other providers have DOI available as an option, which Mailchimp has now done.
  • According to research performed by Litmus, DOI is currently an anomaly and not a common practice. And until it reaches the tipping point and becomes the common practice that the majority of brands are using, then we stand to lose up to 40% of would-be customers. This is because our subscribers and customers aren’t familiar with this process. If it ever were to become the norm, then our subscribers would be accustomed to it and we would have fewer drop-offs.

I’ve written a few posts previously about Double Opt-in, (a couple of them can be read here and here) and I understand that this is an issue that many people are quite vehement about, so I’m trying to tread carefully here…

The two main promoted reasons for using DOI are:

  1. Increased engagement
  2. Increased deliverability

Double Opt-in – Addressing Engagement

Are you rewarded only on engagement? Are your primary KPI’s campaign-based metrics such as opens and clicks? If yes to both of these, then yes, it’s possibly a good idea to use Double Opt-in. DOI can help your campaign metrics look slightly better. Be aware though, that these are vanity metrics and not necessarily evidence of the final objective – but they’re great for reporting on, easy to access and there are numerous tactics you can use to increase these metrics (such as only emailing your actives and ditching your inactives).

However, what price are you paying to make those campaign metrics look good? Potentially you’re not only missing out on sales, but you’re also inadvertently providing the prospect with a bad user experience. What if they don’t know that they haven’t completed the signup process, but they’re waiting and waiting and….waiting for the email and offers you promised them, but sadly, it never arrives. What are they now thinking of your brand?

A transaction took place when they signed up. You made them a promise, they took you up on it and you’ve now failed to deliver upon that promise.

Many email marketers I consult and teach with don’t know about DOI, so why are we expecting the consumer to know about it?

Litmus’ research found that the uplift from using Double Opt-in was not overly compelling, as there were only minimal uplifts in engagement, with the conclusion being that it wasn’t worth the payoff (i.e. loss of subscribers).

What about conversions?

If you’re rewarded on other metrics such as conversions and CLTV, then you may need to consider SOI.

We all know that the greater your reach, the more you can convert – right? It’s simple maths. By using Double Opt-in, you are reducing your reach, as you are losing potentially up to 40% of your subscribers. Therefore if 10,000 people signed up to your list, but 40% failed to complete the DOI process, you now only have permission to email 6,000.

If we were to look at our regular campaigns, which, (let’s say) have an average open rate of 20%, is it the same 20% of your database who open it every time? Of course not. If you calculate your open reach, you’ll see that the total number of people that you reach over a certain period of time is much higher than 20%. In fact, if you’re doing a good job and depending upon how frequently you email them, then you may be reaching 60% of your database over a 6 month or 12 month period .

So, the question is – do you want to reach 60% of 10,000 consumers or 60% of 6,000 people? Remember, the greater your reach, the greater your conversions.

Again, let’s say you have a conversion rate of 2%, would you prefer to convert 2% of 10,000 or 2% of 6,000?

Now, to address the deliverability concerns of not using Double Opt-in

The main reason why Double Opt-in could potentially assist with deliverability is that it can help to stop bots from getting on your list.  But bots can click links within emails as well, so it’s not a fool-proof solution. But there are other alternatives – reCaptcha (or similar) being one, or double entry of the email address being another – both which provide a better user experience AND keep your engaged prospect on your website (who knows – the first conversion may happen!) – rather than direct them to leave the website and go to their email inbox.

The other reason given is engagement. It’s a known fact that the more engaged and active your subscribers are with your campaign, the better deliverability you have. But, whilst in principle, DOI seems to tick the box in providing increased engagement, as Litmus discovered when reviewing the data, the engagement only increases slightly with a Double Opt-in list, and is therefore unlikely to be of any significant benefit to your deliverability.

You’re more likely to increase engagement (plus conversions and deliverability) by implementing strategic lifecycle marketing programmes such as:

  • 1st Purchase Programme (aimed at subscribers who haven’t as yet purchased)
  • Lapsing programme (aimed at those who have shown signs of reduced engagement)
  • Lapsed programme (aimed at those who no longer purchase within an established buying cycle)

As well as implementing a personalisation strategy within your programme and of course, ensuring you’re providing value by supplying the subscriber with the great deals, offers, content etc. that you promised them when they signed up.

In my opinion, Double Opt-in is an archaic best practice, that has been superseded by improved technology. A best practice, that in all honesty, has never had any data to prove that it does deliver on its promises.

That’s not to say some brands don’t have legitimate reasons for using it, as it is a viable option for some brands (such as those who have had past issues with spam traps) – just not every brand. Of course, whether changing from DOI to SOI or vice-versa, I always suggest testing it to ensure it validates your hypothesis.

DOI or SOI; there are cases for using both, so ensure you implement the right approach that is best for you, your brand and your customers/subscribers, and don’t just simply implement DOI because it has the label of being a ‘best practice’.


I’ve been asked to address the issue of spam traps and whether you’re placing yourself at risk by using SOI. This really should be a whole other post, but, for the purpose of this Double Opt-in post, I’ll address the two main types of spam traps that can occur.

The first type (and the very nasty one) is Honey traps, otherwise known as Pristine traps. These are email addresses that have been intentionally created just for this purpose, and planted on websites (often invisible to a person). They act like a honey trap, designed to attract those who scrape addresses off the web and then sell them to some unsuspecting marketer. To avoid this issue, don’t buy or rent lists! Failing that, ensure you’ve verified that the addresses that you’re renting/purchasing are bonafide permission-based lists. Don’t take the provider’s word for it – ask for evidence, as you’ll be the one suffering if they’re not. Whether you do SOI or DOI is irrelevant for this type of spam trap.

ISP’s however also turn malformed addresses into traps as well, so it’s imperative that you reject all malformed addresses such as and, immediately. This can be done technically within your form at the point of subscription, so an email isn’t even sent to this malformed address. Validation tools such as Fresh Address are incredibly helpful here too.

To prevent typos and bots, it’s recommended that you use both the double entry of email address (scripted to prevent copying and pasting within the second field) and re-captcha, and always ensure you have a long field space to enable long email addresses to be seen in full, so the recipient can check they haven’t typed it wrongly.

Another nice technique is once the form is completed, then present the details they’ve provided to them on a landing page for them to check and adjust if necessary.

It’s worth mentioning at this point that if you have an attractive offer, such as a whitepaper etc. then some people may try to access it without giving you a valid email address, knowing that they can download the whitepaper from the landing page.

There are three steps you can take to prevent this from happening:

  • Firstly, add a checkbox to your form saying ‘send me more marketing information’ (or similar – again, another post for another day). The upcoming GDPR legislation is making this a requirement and it can work well for you. If the person wants the content, but doesn’t check the box, then they won’t get the marketing emails they don’t want, only the content they do want – simple! So, ensure you only send marketing info to those who have checked it.
  • Secondly, be upfront with letting them know that they will ONLY receive the asset via email (not on the landing page), meaning that they need to provide you with an active and legitimate email address in order to receive the asset
  • Thirdly, if you’re a business, ask them in the form for their ‘best business email address’ and script it so it rejects yahoo, gmail, outlook etc. domains.

The other type of spam trap is recycled/reused addresses. This is when a person has legitimately signed up to your list at some time in the past, but have either closed their email account or left it dormant. After a certain period of dormancy (this varies between inbox providers), the inbox provider will send hard bounced messages to the emails senders.

However, after a while, they may decide to turn this account into a spam trap and turn off the hard bounces. Therefore, ensure that you stop sending to hard bounced email addresses after the first hard bounce – this way you’ll stay clear of having spam traps on your database.  Again, this type of spam trap can’t be prevented by using a DOI approach on your forms.

Interested in finding out more? Check out how the awesome team at Holistic Email Marketing can help take your email programme to the next level.